Estimating the burden of care for oral potentially malignant disorders and oral cancer in Brazilian dental practice.

BACKGROUND: Oral cancer (OC) and oral potentially malignant disorders (OPMD) pose significant challenges to public health in Brazil. This study aimed to estimate the prevalence of oral cancer (OC) and oral potentially malignant disorders (OPMD) among patients who would be treated by Brazilian dentists during their careers. MATERIAL AND METHODS: Data on the number of dentists in Brazil were extracted from the 2022 census data, while incidence rates for OC cases were sourced from the Brazilian National Cancer Institute (INCA). Population estimates for Brazil and data on dental check-up rates were obtained from relevant national sources. RESULTS: Our analysis indicates that a general dentist in Brazil can expect to encounter on average two to three OC patients and on average 675 patients with OPMDs over a 35-year career. Regional disparities were observed, with certain regions showing higher than the average number of encounters due to low density of dentists in some rural districts. CONCLUSIONS: Brazilian dentists are likely to confront a substantial number of OC and OPMD cases during their professional tenure, emphasizing the need for public health policies aimed at enhancing dental surgeons' education in oral cancer prevention and early detection.

The barriers dentists face to communicate cancer diagnosis: self-assessment based on SPIKES protocol.

BACKGROUND: This study aimed to characterize the barriers faced by Brazilian dentists to deliver bad news (DBN) about oral and oropharyngeal cancer diagnoses to patients by using a questionnaire based on the guidelines of the SPIKES protocol. MATERIAL AND METHODS: This was an observational cross-sectional study. The questionnaire contained 27 questions based on the SPIKES protocol, which were answered in the SurveyMonkey platform. RESULTS: A total of 186/249 dentists answered the questionnaire. The main specialties reported were 36.02% oral medicine, 21.5% oral pathology, and 9.13% oral and maxillofacial surgery. A total of 44.6% expressed concern about the patient's emotional reactions, and 46.24% of respondents had never participated in any specific training to communicate bad news. CONCLUSIONS: The lack of training and low confidence in dealing with patients' emotional reactions dentists were considered the greatest barriers to DBNs. Moreover, most dentists who participated in the survey believe that a protocol to guide the communication of bad news would be useful for clinical practice. For those protocols to be used by dentists, training is critical for these protocols to be incorporated by professionals.

Gingival neoplasms: a multicenter collaborative study of 888 patients in Brazil.

BACKGROUND: To evaluate the prevalence and clinicopathological features of a large series of gingival neoplasms in Brazil. MATERIAL AND METHODS:  All gingival benign and malignant neoplasms were retrieved from the records of six Oral Pathology Services in Brazil, during a 41-year period. Clinical and demographic data, clinical diagnosis, and histopathological data were collected from the patients' clinical charts. For statistical analysis, the chi-square, median test of independent samples and the U Mann-Whitney tests were used, considering a significance of 5%. RESULTS:  From 100,026 oral lesions, 888 (0.9%) were gingival neoplasms. There were 496 (55.9%) males, with a mean age of 54.2 years. Most cases (70.3%) were malignant neoplasms. Nodules (46.2%) and ulcers (38.9%) were the most common clinical appearance for benign and malignant neoplasms, respectively. Squamous cell carcinoma (55.6%) was the most common gingival neoplasm, followed by squamous cell papilloma (19.6%). In 69 (11.1%) malignant neoplasms, the lesions were clinically considered to be inflammatory or of infectious origin. Malignant neoplasms were more common in older men, appeared with larger size, and with a time of complaint shorter than benign neoplasms (p<0.001). CONCLUSIONS:  Benign and malignant tumors may appear as nodules in gingival tissue. In addition, malignant neoplasms, especially squamous cell carcinoma, should be considered in the differential diagnosis of persistent single gingival ulcers.

Oral pigmented lesions: a retrospective analysis from Brazil.

BACKGROUND: Pigmented lesions are uncommon in the oral mucosa, and studies investigating the incidence and types of these lesions are desired to improve the diagnostic knowledge of clinicians. The aim of this study was to analyze the distribution of oral pigmented lesions in a Brazilian population. MATERIAL AND METHODS: A retrospective descriptive cross-sectional study was performed. Oral pigmented lesions were retrieved from the files of two oral and maxillofacial pathology services from Brazil over a 45-year period (1974-2019). The clinical data and the diagnoses of each case were retrieved and included in a Microsoft Excel® database. RESULTS: From 77.074 lesions diagnosed in this period, 761 (0.99%) represented pigmented lesions of the oral mucosa, including 351 (46.1%) melanocytic and 410 (53.9%) non-melanocytic lesions, with a higher incidence in females (73.2%) between the fourth and seventh decades of life. Amalgam tattoo (53.6%) represented the most common lesion, followed by melanotic macule (18.3%) and racial pigmentation (10.8%). Other pigmented lesions included nevus (9.9%), post-inflammatory pigmentation (3%), melanoma (2.1%), melanoacanthoma (1.4%), smoker's melanosis (0.4%), drug-induced pigmentation (0.3%), and melanotic neuroectodermal tumor of infancy (0.1%). The buccal mucosa was the most commonly affected site (25.2%), followed by the alveolar ridge (14.5%), and gingiva (11.8%). CONCLUSIONS: The current findings were similar to previous studies with minor differences due methodology and characteristics of the services from where lesions were retrieved. The knowledge of these data may contribute to a better understanding of oral pigmented lesions and assist clinicians to better recognize and manage them.

What is the frequency of floor of the mouth lesions? A descritive study of 4,016 cases.

BACKGROUND: The aim of this study was to investigate the frequency of oral lesions in the floor of the mouth from representative oral pathology centres in Latin America. MATERIAL AND METHODS: This study was conducted on biopsies obtained from January of 1978 to December of 2018 at nine Latin America oral and maxillofacial pathology centres. Gender, age and histopathological diagnosis were evaluated. Data were analysed using descriptive methods. Chi-square test was used for pairwise comparisons. RESULTS: From 114,893 samples, 4,016 lesions (3.49%) occurred in the floor of the mouth. Brazil showed 3,777 cases (94%), Mexico 182 cases (4.5%) and Argentina 57 cases (1.4%). Benign lesions represented 65.1% (2,617 cases), followed by 34.9% (1,404 cases) of malignant disorders. Lesions of epithelial origin were more frequent (1,964 cases; 48.9%), followed by salivary glands (1,245 cases; 31%) and soft tissue lesions (475 cases; 11.7%). The most common histological subtypes were oral squamous cell carcinoma (1,347 cases; 33.5%), ranula (724 cases; 18%), oral leukoplakia (476 cases; 11.8%) and inflammatory fibrous hyperplasia (239 cases; 5.9%). The lesion affected males in 2,129 cases and females in 1,897 cases. CONCLUSIONS: In the current study, lesions in the floor of the mouth represented 3.49% of biopsies submitted to oral pathology services and oral squamous cell carcinoma, ranula and leukoplakia were the most common lesions.

The impact of head and neck radiotherapy on the dentine-enamel junction: a systematic review.

BACKGROUND: Radiotherapy is widely used in contemporary head and neck cancer treatment protocols. The ability of head and neck radiotherapy (HNRT) to cause direct radiogenic destruction to the teeth is one of the most controversial topics in the field of oral oncology. Therefore, this systematic review aimed to investigate ionising radiation as an independent factor for physical and chemical changes on the dentine-enamel junction (DEJ), a pivotal dental topography for the onset and progression of radiation-related caries (RRC) and enamel delamination. MATERIAL AND METHODS: Systematic searches were conducted on three databases: Scopus, MEDLINE (Via PubMed) and Embase (Elsevier). Laboratory studies evaluating the effects of simulated or in vivo HNRT on the DEJ were included. The GRADE tool adapted for in vitro studies was used to assess the methodological quality. RESULTS: Of the 154 initially selected studies, eight met the inclusion criteria, from which five studies were graded as high quality of evidence, two studies were graded as moderate quality and one as low quality. Two studies did not demonstrate DEJ alterations following HNRT while the other six articles described several organic and inorganic changes in the DEJ of irradiated teeth samples. These radiogenic events were mostly detected through micro and nanoindentation, Raman micro-spectroscopy, confocal microscopy, Western blotting and optical coherence tomography. CONCLUSIONS: HNRT may have a negative impact on the physical and chemical aspects of the DEJ, predisposing cancer patients to RRC and enamel delamination.

Radiographic estimation of the growth rate of initially underdiagnosed ameloblastomas.

BACKGROUND: To evaluate the specific growth rate (SGR) of ameloblastoma. MATERIAL AND METHODS: cases of ameloblastoma initially underdiagnosed (e.g. cases overlooked or diagnosed as reactive lesions) which had adequate radiographic documentation to evaluate their progression were retrospectively selected. Two panoramic radiographs were analyzed to determine the specific growth rate (SGR) of each tumor, defined as the logarithm of the ratio of final tumor area (when the diagnosis of ameloblastoma was made) to the initial tumor area (when the lesion was underdiagnosed), divided by the time interval between the radiographic images. The tumor area was measured using the software ImageJ. RESULTS: Twelve patients with mandibular ameloblastomas were selected, including 5 males and 7 females, with a mean age of 24.9 years (range: 14-61 years). In four cases, the lesion was associated with the crown of an impacted third molar. In three cases, it was initially diagnosed as a periapical lesion. Three cases were extrafollicular and were not noticed in the initial radiographs. Two cases were initially diagnosed as ameloblastoma, but the surgery was delayed for personal reasons. The mean interval of time between the two radiographic images was 4.3 years (range: 0.4-9 years). Based on our analysis, ameloblastoma grows in average 40.4% per year (range: 14.9-88.7%). CONCLUSIONS: Ameloblastoma is a progressively growing tumor, but its growth rate seems to be smaller than initially reported in the literature. Better understanding the radiographic progression of ameloblastoma might improve its early diagnosis, management, and prognosis.

Panoramic and skull imaging may aid in the identification of multiple myeloma lesions.

BACKGROUND: The purpose of this study was to investigate the presence of punched-out lesions in craniofacial bones using three different radiographic protocols in a large cohort of patients. MATERIAL AND METHODS: One hundred fifty-five MM patients were evaluated using panoramic and skull (frontal and lateral) radiographs, which were performed in all patients at the time of MM diagnosis. The diagnostic potential for detecting punched-out lesions was compared among the radiographic techniques. RESULTS: MM punched-out lesions were identified in 135 (87%) panoramic radiographs, 141 (91%) frontal and 144 (93%) lateral skull radiographs. Punched out-lesions were synchronously present in skull and jawbones in 129 (83.23 %) cases. The lesions were detected exclusively in skull in 18 (11.61%) cases and exclusively in jawbones in 6 (3.87%) cases. Punched out-lesion mainly affected the skull and the jawbones in a synchronous way (p<0.001) rather than separately. CONCLUSIONS: All investigated radiographic techniques (panoramic, frontal and lateral skull approaches) demonstrated high detection rates for MM punched-out lesions in craniofacial bones. Panoramic radiography may aid to the radiographic protocols to identify multiple myeloma bone lesions.

Clinical and genetic analysis of patients with cherubism.

OBJECTIVE: To describe the clinical and genetic features of patients with cherubism. MATERIAL AND METHODS: A descriptive analysis of 14 cases from nine different families was carried out. Clinicopathological, imaging, and follow-up data were retrieved from patients' medical files and correlated with the genetic profile of each patient. Genomic DNA isolated from buccal mucosa cells was subjected to direct sequencing analysis of the SH3BP2 gene. RESULTS: Females were more affected than males (8:6), and the mean age at diagnosis was 8.6 years (range 3-30 years). Eleven patients exhibited simultaneous bilateral involvement of the maxilla and mandible. Two patients did not have a familial history of cherubism. Progressive growth pattern was found in six patients and stable lesions were observed in other seven patients, whereas in one patient, complete spontaneous remission was documented during the follow-up (31 years). Mutations were found in 13 cases and included the typical heterozygous missense mutations R415Q, P418T, and P418H at exon 9 of SH3BP2. No correlation between the mutations and the clinical manifestations was observed. CONCLUSION: Three different point mutations in the SH3BP2 gene were detected with variable clinical involvement. Genotype-phenotype association studies in larger population with cherubism are necessary to provide important knowledge about molecular mechanisms related to the disease.

Calcified carotid artery atheromas on panoramic radiographs of head and neck cancer patients before and after radiotherapy.

BACKGROUND: The aims of this study were to verify if head and neck radiotherapy (RT) is able to induce calcified carotid artery atheroma (CCAA) in a large head and neck cancer (HNC) population and also to compare the socio-demographic and clinical findings of patients with and without CCAA detected on panoramic radiographs. MATERIAL AND METHODS: Panoramic radiographs taken before and after head and neck radiotherapy (RT) of 180 HNC patients were selected and analyzed in order to identify the presence of CCAA. In addition, CCAA presence or absence on panoramic radiographs were compared and correlated with clinicopathological findings. RESULTS: A high overall prevalence of CCAA was found on panoramic radiographs (63 out of 180 = 35%) of HNC patients. No significant difference of CCAA before and after RT was observed. There were also no differences between groups (with and without CCAA) regarding age, gender, tobacco and alcohol use, arterial hypertension, diabetes mellitus, acute myocardial infarction, hypercholesterolemia, tumor location, clinical stage of disease and RT dose. However, there was a greater prevalence of strokes in patients with CCAA (p<0.05). CONCLUSIONS: Although CCAA were frequently found in panoramic radiographs of patients with HNC, RT seems not to alter the prevalence of these calcifications.

Metastatic cervical carcinoma of the jaw presenting as periapical disease.

AIM: To present a case report of a metastasis from cervical cancer to the maxilla, which was misdiagnosed as periapical disease and to caution clinicians that metastases could have a disguised clinical presentation that must be taken into account in the differential diagnosis of periapical disease in oncologic patients. SUMMARY: Although metastatic tumours of the jaws are uncommon, they may mimic benign inflammatory processes and reactive lesions. The ability of metastatic lesions to mimic periapical disease is discussed and a brief review of the literature is presented, emphasizing the importance of correct diagnosis to prevent delay in diagnosing cancer. Attention should therefore be given to the patient's medical history, especially of those with a previous history of cancer, and all dental practitioners should be aware of the possibility of metastases that may be confused with periapical disease. Finally, endodontists are well placed to recognize malignant and metastatic oral lesions during the initial clinical stages, given that their treatments are usually based on frequent dental appointments and long-term follow-ups.

The wolf in sheep's clothing: Microtomographic aspects of clinically incipient radiation-related caries.

BACKGROUND: Radiation related caries (RRC) can cause rapid progression, with a high potential for dental destruction affecting mainly cervical and incisal areas. Unlike the injuries that occur in the conventional caries, incipient RRC present in unusual surfaces have difficult diagnosis and classification stages of cavitation. MATERIAL AND METHODS: Evaluate the radiographic patterns of demineralization of RRC by using micro-CT. Ten teeth with incipient RRC and 10 teeth with incipient conventional caries (control group) matched by anatomic teeth group and caries affected surfaces were evaluated by X-ray microtomography (micro-CT) Skyscan 1174V2 (50Kv, 1.3 megapixel, Kontich, Belgium). Teeth were placed in a standard position for micro-CT (coronal, transaxial and sagittal sections) during images acquisition. Lesions were classified according to the depth of invasion and relationship with enamel, dentin and pulp. RESULTS: RRC samples presented deeper lesions with higher involvement of enamel and dentin. Control group presented focal and superficial lesions with lower involvement of enamel and dentin. CONCLUSIONS: Incipient RRC present aggressive microtomographic patterns of demineralization when compared to conventional caries, as indicated by deep lesions, regardless of its clinically incipient aspects.

Processing strategies for smart electroconductive carbon nanotube-based bioceramic bone grafts.

Electroconductive bone grafts have been designed to control bone regeneration. Contrary to polymeric matrices, the translation of the carbon nanotube (CNT) electroconductivity into oxide ceramics is challenging due to the CNT oxidation during sintering. Sintering strategies involving reactive-bed pressureless sintering (RB + P) and hot-pressing (HP) were optimized towards prevention of CNT oxidation in glass/hydroxyapatite (HA) matrices. Both showed CNT retentions up to 80%, even at 1300 °C, yielding an increase of the electroconductivity in ten orders of magnitude relative to the matrix. The RB + P CNT compacts showed higher electroconductivity by ∼170% than the HP ones due to the lower damage to CNTs of the former route. Even so, highly reproducible conductivities with statistical variation below 5% and dense compacts up to 96% were only obtained by HP. The hot-pressed CNT compacts possessed no acute toxicity in a human osteoblastic cell line. A normal cellular adhesion and a marked orientation of the cell growth were observed over the CNT composites, with a proliferation/differentiation relationship favouring osteoblastic functional activity. These sintering strategies offer new insights into the sintering of electroconductive CNT containing bioactive ceramics with unlimited geometries for electrotherapy of the bone tissue.

A new sheep model with automatized analysis of biomaterial-induced bone tissue regeneration.

Presently, several bone graft substitutes are being developed or already available for clinical use. However, the limited number of clinical and in vivo trials for direct comparison between these products may complicate this choice. One of the main reasons for this scarcity it is the use of models that do not readily allow the direct comparison of multiple bone graft substitutes, due especially to the small number of implantation sites. Although sheep cancellous bone models are now well established for these purposes, the limited availability of cancellous bone makes it difficult to find multiple comparable sites within a same animal. These limitations can be overcome by the monocortical model here proposed as it consists in 5-6 holes (5 mm Ø), in the femoral diaphysis, with similar bone structure, overlying soft tissue and loading pattern for all defects. Associated to this model, it is also described a fast histomorphometric analysis method using a computer image segmentation test (Threshold method) to assess bone regeneration parameters. The information compiled through the experimental use of 45 sheep in several studies allowed determining that this ovine model has the potential to demonstrate differences in bone-forming performance between various scaffolds. Additionally, the described histomorphometric method is fast, accurate and reproducible.

Antibacterial, physicochemical and mechanical properties of endodontic sealers containing quaternary ammonium polyethylenimine nanoparticles.

AIM: To evaluate the antibacterial, physicochemical and mechanical properties of two endodontic sealers incorporating quaternary ammonium polyethylenimine (QPEI) nanoparticles at concentrations of 1% and 2% (w/w). METHODOLOGY: The sealers tested were AH Plus and Pulp Canal Sealer EWT in the commercial unmodified form or containing 1% or 2% QPEI. Antibacterial activity was evaluated using a direct contact test (DCT) against Enterococcus faecalis ATCC 29212 and two endodontic isolates (RW35 and RN44). Sealers freshly mixed or set for 7 days were exposed to bacterial suspensions for 10, 30 and 60 min. Setting time, flow test, solubility, apparent porosity, dimensional change following setting, wettability, zeta potential and compressive strength were assessed according to the International Standard Organization 6876:2001 (ISO 6876). RESULTS: DCT results revealed that both freshly prepared sealers had antibacterial effects unaffected by QPEI incorporation. Both unmodified sealers had lost much of their antibacterial effects after 7 days. However, for Pulp Canal Sealer EWT incorporated with 1% and 2% QPEI nanoparticles, the antibacterial effects against all test E. faecalis strains within 30 and 60 min of contact were significantly greater than the unmodified formula. Addition of QPEI resulted in no significant increase in the antibacterial effects of AH Plus after ageing. As for physicochemical and mechanical tests, setting time, wettability and zeta potential were influenced by the presence of QPEI nanoparticles. CONCLUSION: Incorporation of QPEI nanoparticles can improve the long-term antibacterial activity of Pulp Canal Sealer EWT without relevant changes in physicochemical and mechanical properties.

Biological evaluation of alginate-based hydrogels, with antimicrobial features by Ce(III) incorporation, as vehicles for a bone substitute.

A novel hydrogel, based on an alginate/hyaluronate mixture and Ce(III) ions, with effective bioactive and antimicrobial ability was developed to be used as vehicle of a synthetic bone substitute producing an injectable substitute (IBS). Firstly, three different IBSs were prepared using three developed alginate-based hydrogels, the hydrogel Alg composed by alginate, the hydrogel Alg/Ch composed by an alginate/chitosan mixture and the hydrogel Alg/HA composed by an alginate/hyaluronate mixture. MG63 cells viability on the IBSs was evaluated, being observed a significantly higher cell viability on the Alg/HA_IBS at all time points, which indicates a better cell adaptation to the material, increasing their predisposition to produce extracellular matrix and thus allowing a better bone regeneration. Moreover, SEM analysis showed evident filopodia and a spreader shape of MG63 cells when seeded on Alg/HA_IBS. This way, based upon the in vitro results, the hydrogel Alg/HA was chosen to the in vivo study by subcutaneous implantation in an animal model, promoting a slight irritating tissue response and visible tissue repairing. The next step was to grant antimicrobial properties to the hydrogel that showed the best biological behavior by incorporation of Ce(III) ions into the Alg/HA, producing the hydrogel Alg/HA2. The antimicrobial activity of these hyaluronate-based hydrogels was evaluated against Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Candida albicans. Results showed that Ce(III) ions can significantly enhance the hydrogel antimicrobial ability without compromising the osteoconductivity improvement promoted by the vehicle association to the synthetic bone substitute.

Cleidocranial dysplasia: oral features and genetic analysis of 11 patients.

BACKGROUND: Cleidocranial dysplasia (CCD) is a dominantly inherited autosomal disease characterized by typical bone defects including short stature, persistently open or delayed closure of the cranial sutures, and hypoplastic or aplastic clavicles. Oral features are frequent and include supernumerary teeth, delayed eruption or impaction of the permanent teeth, and malocclusion. Heterozygous mutations in RUNX2 gene, which encodes a transcription factor essential for osteoblast differentiation, were identified as the etiological cause of CCD. OBJECTIVE AND METHODS: Herein, we performed physical and radiographic examination and screening for RUNX2 mutations in 11 patients from five families with CCD. RESULTS: All patients demonstrated the classical phenotypes related to CCD. Families whose affected members had several dental alterations such as multiple impacted and supernumerary teeth demonstrated heterozygous missense mutations (R190Q and R225Q) that impair the runt domain of RUNX2. On the other hand, CCD patients from families with low frequency of dental abnormalities showed no mutation in RUNX2 or mutation outside of the runt domain (Q292fs→X299). CONCLUSION: The current findings suggest a correlation between dental alterations and mutations in the runt domain of RUNX2 in CCD patients. Further clinical and genetic studies are needed to clarify the relationship between phenotypes and genotypes in CCD and to identify other factors that might influence the clinical features of this uncommon disease.

Antimicrobial profile of a dental implant abutment coating to prevent adhesion and migration of bacteria and screw loosening.

OBJECTIVE: Failure of dental implants treatment is frequently the result of bacterial colonization of implants followed by diseases like peri-implantitis. Recent studies have been made regarding the surface treatment of implants components, namely abutments that are in the interface of the living tissue with the implant. This work aimed at evaluating the antimicrobial profile of a silane-based coating with TiO2 adapted to an abutment screw, that was also developed as an anti-loosening agent, to prevent adhesion and migration of Gram + and Gram-bacteria, Staphylococcus aureus, and Escherichia coli, respectively. METHODS: Direct contact antimicrobial studies were conducted on coated and uncoated samples by resazurin fluorescent assay and cytotoxicity assessment was done via MTT indirect method on days 1 and 4. Sterilizations studies by FTIR analysis were also performed to understand the ideal balance between sterilization efficacy and coating functionality subjecting the samples to ethylene oxide, gamma irradiation, and autoclave sterilization, before antimicrobial testing. The implant system as a whole was also studied for its ability to block bacterial migration and preventing microleakage as well as an assessment of initial bacterial adhesion evaluated by scanning electron microscopy. RESULTS: Direct contact studies performed on coated samples showed a very high antimicrobial activity, while cytotoxicity assays revealed the coating to be safe and non-leachable. Sterilizations studies showed that the antimicrobial features of the coating were preserved and interchangeable regardless of the sterilization method. The implant system migration studies demonstrated that the implant system works as an efficient barrier for the studied bacteria. SIGNIFICANCE: The acquired results clearly show that it is possible to obtain a highly functional coating with obvious and marked antimicrobial features that together with an abutment that prevents bacterial migration and versatility in sterilization methodology has a very high potential in the dental implant field.

Mechanical behavior of ropes based on polypropylene (PP) and poly(ethylene terephthalate) (PET) multifilament yarns for Achilles tendon partial substitution.

In some clinical cases, attending to the type and extension of the Achilles tendon injury, a partial replacement of the tissue may be needed. Driven by this, the authors developed different structures based on polypropylene (PP) or poly (ethylene terephthalate) (PET) multifilament yarns, using a textile technology-based technique, in order to mimic the fibrous structure of tendons. Those structures are based on a core/shell system, being the core composed by several sub-components (braids) and the shell based on braided yarns enclosing the core. It was observed that the load at failure of ropes is mainly defined by the number of yarns that compose it, but the strain level is mostly influenced by the production take-up rate of the core braids and consequently by the braid angle. The ropes stiffness level results from a combination of the yarns number and braid angle of the core braids. The structure based on PET yarns revealed a non-linear force-strain curve similar to a typical curve of a natural Achilles tendon (AT), presenting a load at failure, strain to failure and stiffness levels very promising for AT replacement. Moreover, the PET rope also revealed a very promising fatigue and appropriate creep resistance for the final application, being in accordance with what has been reported for native AT.

Patterns of demineralization and dentin reactions in radiation-related caries.

Radiation-related caries is a unique form of rampant decay and is a complication of head and neck radiotherapy that frequently causes generalized dental destruction and impairs quality of life in cancer patients. The aim of this study was to investigate the patterns of demineralization of caries in irradiated patients and to establish whether direct radiogenic damage to the dentition might be important in the progression of radiation-related caries. Teeth from patients who had concluded radiotherapy were examined histologically by polarized light microscopy, and the ultrastructure was examined by scanning backscattered electron microscopy. Cervical caries and incisal caries, a very unusual sort of lesion, were widely detected. Additionally, diffuse brown discoloration of the smooth surface of enamel was frequently observed. Polarized light microscopy suggested that these areas were incipient caries. Evidence of normal odontoblast function was observed in the detection of reactionary dentin and intratubular dentin deposition. In conclusion, radiation-related caries seems to have the same morphological and demineralization pattern as ordinary caries, with the presence of demineralized dentin, a translucent zone, dentin dead tracts, reactionary dentin and intratubular dentin deposition. Based on these findings, direct radiogenic destruction of the teeth seems to be not essential to the microscopic progression of radiation-related caries.